Studies on Bacillus thuringiensis strains isolated from Swedish soils: insect toxicity and production of B. cereus-diarrhoeal-type enterotoxin

At moderate concentration, 23 of 40 strains of Bacillus thuringiensis isolated from Sweden were toxic to Trichoplusia ni and five were toxic to Aedes aegypti. Five of the strains were toxic to Diabrotica undecimpunctata at high concentration, two were toxic to Heliothis virescens at low concentration and five produced thuringiensin (formerly called -exotoxin). No strain was toxic towards the beet armyworm Spodoptera exigua at low concentration. Twenty-three of the strains produced a B. cereus-diarrhoeal-type enterotoxin.A. Abdel-Hameed is with the Department of Microbiology, Faculty of Pharmacy, Cairo University, Kasr-El-Aini Street, Cairo, Egypt. R. Landén is with the Department of Microbiology, Stockholm University, S-10691 Stockholm, Sweden. A. Abdel-Hameed's present address is the Department of Applied Chemistry and Microbiology, P. O. Box 27, Viikki, Building B, FIN-00014 University of Helsinki;     

Immobilization of Zymomonas mobilis 2716, for the protection of cellular activity

Alginate-immobilized Zymomonas mobilis cells produced 17.8% (v/v) ethanol in less than 24 h, with an ethanol yield of 97%, compared with 88% for free cells, using a fed-batch cultivation technique. The substrate, glucose, was added intermittently in powder form to foster nucleation of the CO₂ formed. Repeated-batch cultivation led to complete utilization of approximately 200 g glucose/l in 7.5 h with a 98% conversion efficiency to ethanol. Free cells used the glucose less efficiently (conversion efficiency of 78%), and even after 100 h the glucose was not fully consumed. Freeze-substitution electron microscopy studies showed that immobilized cells generally displayed lesser blebbing and membrane disruption than free cells. These studies further suggest that membrane blebbing may be due to an effect of high initial glucose levels, and not due to the accumulation of end-products ethanol and CO₂.L.A. Kirk, H.W. Doelle and R.I. Webb are with the Department of Microbiology, University of Queensland, Brisbane, QId 4072, Australia. R.I. Webb is also with the Microscopy and Microanalysis Centre, University of Queensland, Brisbane, QId 4072, Australia;     

Exopolysaccharide production by Acremonium diospyri in continuous culture

Production of an exopolysaccharide (glucan) by Acremonium diospyri was not markedly affected by its specific growth rate, the culture pH or the stirrer speed under NH ₄ ⁺ -limiting chemostat conditions. The exopolysaccharide was also detected in the medium under conditions of NH ₄ ⁺ excess.P. Wood and R.J. Seviour are with the Biotechnology Research Centre, La Trobe University College of Northern Victoria, Bendigo, Victoria 3550, Australia     

Detection of Vibrio cholerae O1 in the aquatic environment in Brazil employing direct immunofluorescence microscopy

Culturing and immunofluorescence (FA) methods for detection of Vibrio cholerae O1 in samples collected from the aquatic environment at selected sites in Brazil were compared. Of the samples examined, 90% were positive for V. cholerae O1 by FA but none was positive by culture, although strains of V. cholerae other than O1 strains were readily isolated. Evidence for V. cholerae O1 being autochthonous to the aquatic environment of Brazil is presented. Furthermore, FA methods are recommended for cholera surveillance programmes directed at the natural environment.M.T. Martins is with the Department of Microbiology, I.C.B. II, University of Sao Paulo, Sao Paulo, S.P. CEP 05508, Brazil. P.S. Sanchez and M.I.Z. Sato are with the State Agency for Environmental Control-CETESB, Sao Paulo, S.P. CEP 05459, Brazil. P.R. Brayton and R.R. Colwell are with the Department of Microbiology, University of Maryland, College Park, MD 20742, USA; R.R. Colwell is also with the Center of Marine Biotechnology, Maryland Biotechnology Institute, 600 East Lombard St, Baltimore, MD 21202, USA.     

Astaxanthin production by a Phaffia rhodozyma mutant on grape juice

During fermenter cultivation of Phaffia rhodozyma on a grape juice medium, the presence of glucose initially delayed fructose utilization, although fructose was consumed before glucose depletion. Total pigment and astaxanthin production were growth associated and reached maximum values of 15.9 g/ml and 9.8 g/ml, respectively, after depletion of the carbon source. The total cellular pigment and astaxanthin content increased during the stationary growth phase due to a decrease in biomass, reaching final values of 2120 g/g and 1350 g/g, respectively, without the volumetric concentration in the culture changing. The final cell yield was 0.33 g/g sugar utilized. High sugar concentrations in shake-flasks as well as O₂ limitation decreased the astaxanthin content of the cells. Addition of yeast extract to a grape juice minimal medium markedly increased the maximum specific growth rate, total pigment and astaxanthin content of the cells. An excess of ammonia decreased the intracellular astaxanthin content, which reached a maximal value in cultures with no residual glucose or ammonia.The authors are with the Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, Bloemfontein 9300, South Africa;     

Culture conditions for yellow pigment formation byMonascus sp. KB 10 grown on cassava medium

An isolate ofMonascus, from a commercial, fermented soybean curd (sufu) was grown on a cassava medium. With medium at an initial pH of 7.0 an orange-red pigmentation was produced but with an initial pH below 4, a light golden pigment was obtained. A medium containing, w/v, 3% cassava starch, 0.4% peptone and 0.1% glutamic acid, with an initial pH of 2.5 was optimal for the production of this yellow pigment, which had a single maximum absorption spectrum at 330 nm. The spectroscopic characterization of the purified yellow pigments demonstrated a monascin-ankaflavin-monascorubrin skeleton.B. Yongsmith, W. Tabloka and W. Yongmanitchai are with the Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. R. Bavavoda is with the Department of Botanical Pharmacy, Chulalongkorn University, Bangkok, Thailand.     

Pathways of pyruvate metabolism and energetics of growth of Brochothrix thermosphacta

Brochothrix thermosphacta, a psychrophilic, facultative anaerobe, exhibited homolactic fermentation under anaerobic conditions in the presence of excess glucose. In glucose-limited chemostat culture (on synthetic medium), ethanol, acetate, formate and lactate were formed. Formation of ethanol and acetate was accounted for by the formate concentrations in culture filtrates. Acetate, formate and ethanol formation was enhanced at low growth rates in chemostat culture. O₂-limited chemostat studies indicated that formate formation was inhibited by oxygen (<0.2 M) and studies with a variant, strain 301, which lacked pyruvate dehydrogenase activity, showed that cell culture in basal medium did not occur at O₂ tensions greater than that preventing formate production in the wild-type strain. The data are consistent with stimulation of pyruvate formate lyase activity by glucose limitation, possibly because of decreased concentrations of glycolytic intermediates.S.P. Singh was and A. Garrett and P.J. Rogers are with the Division of Science and Technology, Griffith University, Brisbane 4111, Australia. J. McAvoy and A.F. Egan are with the CSIRO Meat Research Laboratory, Cannon Hills, Brisbane 4170, Australia. S.P. Singh is now with the Department of Microbiology, C.B.S. & H., G.B. Pant University of Agriculture & Technology, Pantnagar-263145, India.     

Distribution of Bacillus thuringiensis strains in Southern Sweden

Bacillus thuringiensis strains were found to be naturally present in the soils of southern Sweden, being isolated from nine out of 12 sites examined. Forest soil samples were more rich in B. thuringiensis strains than soil samples collected from cultivated areas. A wide diversity of B. thuringiensis strains, representing different biochemical groups, was isolated; samples from Aspö and Fogdö regions showed the highest degree of diversity.R. Landén and M. Bryne are with the Department of Microbiology, Stockholm University, S-10691 Stockholm, Sweden. A. Abdel-Hameed is with the Department of Microbiology, Faculty of Pharmacy, Cairo University, Kasr-El-Aini Street, Cairo, Egypt. A. Abdel-Hameed's present address is the Department of Applied Chemistry and Microbiology, PO Box 27, Viikki, Building B, SF-00014 University of Helsinki, Helsinki, Finland     

Capsule formation in Zymomonas mobilis grown on sucrose

A capsule formed around Zymomonas mobilis grown on sucrose, increasing in thickness with higher initial sucrose concentrations. Cryofixation and freeze-substitution electron microscopy techniques preserved this polymer matrix, unlike other techniques.L.A. Kirk and R.i. Webb are with the Department of Microbiology, The University of Queensland, Brisbane, Qld 4072, Australia; R.I. Webb is also with the Centre for Microscopy and Microanalysis and H.W. Doelle is with MIRCEN-Brisbane, both at The University of Queensland, Brisbane, Qld 4072, Australia.     

Ribonuclease production by free and immobilizedAspergillus clavatus cells

Several fungal strains ofAspergillus andPenicillium were immobilized by cryopolymerization in polyvinyl alcohol cryogel beads.Aspergillus clavatus was the best producer of extracellular ribonuclease. Enzyme productivity and growth of free and immobilized cells in shake flasks and agitated bioreactor were studied. Ribonuclease production and growth behaviour depended on concentrations of glucose, peptone and soybean in the culture medium. Enzyme production was influenced by agitation and aeration intensity. In repeated batch, shake-flask cultures, the immobilized cells showed 2 to 3.5 times higher enzyme activity than free cells. The optimal conditions in a bioreactor were at 150 rev/min agitation speed and 0.5 vol/vol.min aeration. Enzyme productivity of immobilized cells (237 units/g dry mycelium.h) was 2.1 times higher than the productivity of free cells in a bioreactor, and 2.3 times higher than that of a shake-flask culture.R.J. Manolov is with the Institute of Microbiology, Department of Enzymes, Bulgarian Academy of Sciences, Georgy Bonchev Street 26, 1113 Sofia, Bulgaria.     

Light-independent conidiation in Trichoderma spp.: a novel approach to microcycle conidiation

Microcycle conidiation in Trichoderma hamatum and T. harzianum has been achieved in complete darkness for the first time. The time required for mass conidiation without intervening vegetative growth was decreased to 24 h instead of 6 to 7 days. The conidia produced by microcycle conidiation were viable and had pigmentation and antagonistic behaviour similar to those of the parental stock cultures.N. Khurana, R.K. Saxena, R. Gupta and R.C. Kuhad are with the Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021, India.     

Protein enrichment of lignocellulose resulting from the growth of two Streptomyces strains

Two Streptomyces strains were grown on sugarcane bagasse and groundnut hulls lignocelluloses in semi-solid state culture at 37°C for 12 weeks. Best results gave a 45% depletion of sugarcane bagasse lignocellulose with a 21% crude protein content of final material. The possibility of using S. viridosporus to improve the protein content of both lignocelluloses for use as an animal feedstock supplement is discussed.At the time of this research the authors were with the Department of Biological Sciences, Rivers State University of Science & Technology, PMB 5080, Port Harcourt, Nigeria and the Department of Biological Sciences, University of Calabar, PMB 1115, Calabar, Nigeria. Dr lyo is now with the Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.     

Toxicity of the blue-green alga Oscillatoria agardhii to the mosquito Aedes aegypti and the shrimp Artemia salina

The cyanobacterium Oscillatoria agardhii 27, which does not produce mammalian neuro- or hepatotoxins, was highly toxic to the larval stages of the yellow fever mosquito Aedes aegypti: its 24-h LC₅₀ values against fourth-and second-instar larvae of A. aegypti were 8.7 and 6.1 g live cells/ml, respectively. The toxin was water-soluble and was partially purified but the chemical nature of the toxic compound(s) is still unknown. Aqueous solutions were also toxic to the newborn larvae of the brine shrimp, Artemia salina, used for the bioassay. The toxic activity of these solutions decreased markedly on heating to 90°C for 15 min.J. Kiviranta is with the Department of Pharmacy, P.O. Box 15, FIN-00014 University of Helsinki, Helsinki, Finland; A. Abdel-Hameed is usually with the Department of Microbiology, Faculty of Pharmacy, Cairo University, Kasr-El-Aini Street, Cairo, Egypt, but is presently with the Department of Applied Chemistry and Microbiology, P.O. Box 27, Viikki, Building B, FIN-00014 University of Helsinki, Helsinki, Finland.     

Effects of genotoxic agents on his + revertants and survival of spores of Streptomyces aureofaciens

The effects of u.v. light and of several chemical agents on spores of the tetracycline producer Streptomyces aureofaciens MT1 were studied using survival curves and induction of histidine prototrophic revertants (his ⁺). Spores were highly resistant to u.v.; NTG induced most his ⁺ revertants. 4-Nitroquinoline-1-oxide and methyl methanesulphonate also gave good yields of revertants. Whereas ethyl methanesulphonate had the least effect on inducing the revertants.M. Marins is with the Department of Biochemistry, Institute of Chemistry, University of São Paulo, SP, Brazil. S.O.P. Costa and G. Padilla are with the Department of Microbiology, Biomedical Science Institute, University of São Paulo, Avenida Prof. Lineu Prestes 1374, SP, Brazil, CEP 05508-900     

Decoloration of azo dyes by three whiterot fungi: influence of carbon source

Two strains of Phanerochaete chrysosporium and a local isolate of white-rot fungus, if pre-cultured in a high nitrogen medium with glucose, could decolorize two azo dyes (Amaranth and Orange G) and a heterocyclic dye (Azure B). When starch was used in the pre-cultivation medium, decoloration of Orange G occurred if the medium also contained 12mM NH₄Cl, whether or not veratric acid was present. In medium containing 1.2mM NH₄Cl and veratric acid, greater decoloration occurred with one strain of P. chrysosporium and the local isolate. In preculture medium with cellulose and 1.2mM NH₄Cl, decoloration by the local isolate was enhanced but not that by the other strains.The authors are with the Department of Microbiology, Soochow University, Shih Lin, Taipei, Taiwan     

Growth kinetics of Aeromonas hydrophila in freshwaters supplemented with various organic and inorganic nutrients

Freshwaters of varying natural nutrient enrichment were used as growth media for the culture of an autochthonous, heterotrophic, freshwater bacterium, Aeromonas hydrophila. The growth rate of the bacterium in eutrophic waters was increased to the greatest extent by adding carbon, as glucose; generation times decreased by up to 65%. Additions of carbon and phosphorus increased the maximal cell densities by over 25-fold. In oligotrophic waters, bacterial growth was most strongly promoted by the simultaneous additions of carbon (as glucose) and phosphorus (as KH₂PO₄). In these waters, stationary phase densities were increased as much as 100-fold, with a corresponding 70% increase in growth rate. These data provide at least a partial explanation for the previously observed correlation between A. hydrophila densities and the trophic states of freshwaters.The authors are with the Department of Microbiology, Morrill Hall, University of Rhode Island, Kingston, Rhode Island 02881, USA     

Role of membrane potential in ammonium inhibition of nitrogenase activity in the cultured cyanobiont Nostoc ANTH

Ammonium at 5mM completely inhibited nitrogenase activity of Nostoc ANTH but only slightly inhibited the membrane potential, indicating that these two events are independent and that nitrogenase activity is not regulated by the latter.B.B. Singh and P.S. Bisen are with the Department of Microbiology, Barkatullah University, Bhopal-462026, India; S. Singh was with the Department of Microbiology, Barkatullah University, Bhopal, India; he is now with the Department of Microbiology, North Maharastra University, Jalgaom-425001, India.     

The kinetics and regulation of M-xylose transport in Candida utilis

Low-affinity (K _m=67.6±3.2 mM) and high-affinity (K _m=1.9±1.2 mM) D-xylose transport occur in Candida utilis grown, respectively, on D-glucose or D-xylose. Starvation of glucose-grown cells decreases the K _m value (10.5±2.6 mm). The high-affinity system appearing during starvation required protein synthesis and it was inactivated when cells were exposed to glucose, by a process independent of protein synthesis. High-affinity transport was accompanied by transient alkalinization of yeast suspensions, indicating that it is a proton symport, whereas low-affinity transport was not. Both systems, however, were inhibited by metabolic inhibitors and by replacing H₂O in the transport assay with D₂O, indicating that both may be proton symports. Glucose and acetic acid also inhibited both high-and low-affinity xylose transport.S.G. Kilian, B.A. Prior and J.C. du Preez are with the Department of Microbiology and Biochemistry, University of the Orange Free State, P.O. Box 339, Bloemfontein 9300, Republic of South Africa     

Polysaccharide production by Aureobasidium pullulans: factors affecting polysaccharide formation

Aureobasidium pullulans NRRL 6220 synthesized polysaccharide most actively in media containing sucrose, fructose or maltose with (NH₄)₂SO₄ (0.6 g/l) or ammonium acetate giving greatest yields of the polysaccharide. With (NH₄)₂SO₄ at 1.2 g/l, production of polysaccharide was decreased considerably. Polysaccharide production was highest with an initial pH of 6.5 while biomass formation was better below an initial pH of 5.5. Optimum phosphate concentration for polysaccharide production was 0.03 m.S.M. Badr-Eldin, H.G. El-Masry and O.A. Abd El-Rahman are with the Microbial Chemistry Department, National Research Center, Dokki, Cairo, Egypt; F.H.A. Mohamad is with the Chemical Engineering and Pilot Plant Department, National Research Center, Dokki, Cairo, Egypt. O.M. El-Tayeb is with the Microbiology Department, Faculty of Pharmacy, Cairo University, Egypt.     

A new species of Gigaspora from desert soils of Rajasthan,India

A new species of the endogonaceous fungus Gigaspora, isolated from the Indian semi-arid region, is described. The fungus, named G. tuberculata, produces rusty-brown azygospores with septate subtending hypha. The azygospores bear warts all over the outer wall. The shape, size and general appearance of these spores resemble those of Scutellospora persica.Neeraj and A.K. Varma are with the Microbiology Unit, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110 067, India; K.G. Mukerji is with the Applied Mycology Laboratory, Botany Department, University of Delhi, Delhi 110 006, India. B.C. Sharma is with the Department of Textile Engineering, Indian Institute of Technology, New Delhi 110 016, India.